KR20040067424A - Method for preparing of acrylonitrile-butadiene-styrene graft copolymer - Google Patents

Abstract

PURPOSE: A method for preparing acrylonitrile-butadiene-styrene(ABS) graft copolymers is provided to improve the graft ratio, the molecular weight of acrylonitrile-styrene copolymer and productivity, and to obtain excellent impact resistance, chemical resistance and thermal stability. CONSTITUTION: The method for preparing ABS graft copolymers comprises the step of polymerizing a polybutadiene rubbery polymer, an aromatic vinyl compound and vinyl cyanide compound by using a peroxide, an activating agent and a reducing agent. The peroxide is used in an amount of 0.05 to 0.5 parts by weight, the activating agent is used in an amount of 0.0004 to 0.005 parts by weight and the reducing agent is used in an amount of 0.001 to 0.05 parts by weight, each based on 100 parts by weight of the monomers.

Description

Method for preparing acrylonitrile-butadiene-styrene graft copolymer {METHOD FOR PREPARING OF ACRYLONITRILE-BUTADIENE-STYRENE GRAFT COPOLYMER}

The present invention relates to a method for producing an acrylonitrile-butadiene-styrene graft copolymer, and more particularly, to improve the graft ratio, the molecular weight of the acrylonitrile-styrene copolymer, and the productivity, and at the same time impact resistance. The present invention relates to a thermoplastic resin composition having significantly improved impact strength, including a method for preparing an ABS graft copolymer having excellent chemical resistance, thermal stability, and an ABS graft copolymer prepared by the above method.

Acrylonitrile-butadiene-styrene (ABS) graft copolymer resins are formulated with rubber components to improve impact resistance to copolymers of acrylonitrile and styrene, which have excellent dimensional stability, processability, and chemical resistance. In addition, it is used as a material for monitor housings, game machine housings, home appliances, office equipment, and the like.

In general, the following methods are used to disperse the rubber component in the ABS graft copolymer resin. First, a method of bulk polymerization by dissolving a rubber component in acrylonitrile and styrene, a monomer, and a method of solution polymerization by dissolving a rubber component in monomers, acrylonitrile and styrene, and a third solution of arc in a rubber polymer. There is a method of grafting rironitrile and styrene by emulsion polymerization method.

However, the rubber particle size of the rubber-reinforced thermoplastic resin obtained by dispersing the rubber component in the acrylonitrile-styrene copolymer resin by the bulk polymerization method and the solution polymerization method is several μm, and the gloss is lowered, thereby limiting its use. There is a problem with receiving.

In addition, the size of the rubber particles of the rubber-reinforced thermoplastic resin obtained by grafting by the emulsion polymerization method is 1 ㎛ or less, there is an advantage that the gloss is excellent.

The emulsion polymerization method is based on a batch reaction, not a continuous reaction, unlike the bulk polymerization or solution polymerization. In general, the batch reaction is lower in productivity than the continuous reaction, and in order to overcome this, a graft copolymer having a high rubber content is prepared, and then mixed with a styrene copolymer prepared in a continuous reaction to obtain a suitable rubber content. Productivity is increasing by making rubber-reinforced thermoplastics. That is, the rubber content of the final resin composition is adjusted by controlling the content of the graft copolymer and the styrene copolymer having a high rubber content according to the purpose of use. In addition, the physical properties of the final resin composition may be adjusted by controlling the monomer composition ratio of the styrene copolymer used for mixing.

Meanwhile, the productivity of the ABS graft copolymer prepared by the batch reaction is much lower than that of the styrene copolymer prepared by the continuous reaction. As a method for overcoming this, the composition of the ABS graft copolymer prepared by the emulsion polymerization is A method of increasing the butadiene content is used.

The ABS graft copolymer prepared by the above method has a reduced content of acrylonitrile and styrene to be grafted as the butadiene content is increased in the composition, so that the graft ratio (the weight of the copolymer grafted to the unit gram of butadiene rubber is expressed as a percentage). The lower the molecular weight of the grafted acrylonitrile-styrene copolymer. The lowering of the graft ratio and the molecular weight of the acrylonitrile-styrene copolymer lowers the thermal stability and impact resistance of the ABS graft copolymer, and the rubber-reinforced thermoplastic resin composition containing the ABS graft copolymer has a limitation on the use purpose. There is a problem that you will receive.

Therefore, there is a need for further research on a method for producing an ABS graft copolymer having excellent graft ratio and at the same time improving molecular weight of the acrylonitrile-styrene copolymer having excellent thermal stability and impact resistance.

In order to solve the problems of the prior art as described above, the present invention provides a method for producing an acrylonitrile-butadiene-styrene graft copolymer that can significantly improve the graft rate, the molecular weight of the acrylonitrile-styrene copolymer, and productivity. It aims to do it.

It is another object of the present invention to provide an ABS graft copolymer composition prepared by the above method and excellent in impact resistance, chemical resistance, and thermal stability.

Still another object of the present invention is to provide a thermoplastic resin composition having significantly improved impact strength, including the ABS graft copolymer.

In order to achieve the above object, the present invention comprises a step of polymerizing a polybutadiene rubber polymer, an aromatic vinyl compound, and a vinyl cyan compound using a peroxide, an activator, and a reducing agent in a method for producing an ABS graft copolymer. It provides a method for producing an ABS graft copolymer.

The present invention also provides an ABS graft copolymer composition prepared by a method comprising polymerizing a polybutadiene rubber polymer, an aromatic vinyl compound, and a vinyl cyan compound using a peroxide, an activator, and a reducing agent.

In addition, the present invention is a thermoplastic resin composition,

a) in polybutadiene rubber using peroxides, activators and reducing agents

To polymerize coalescing, aromatic vinyl compounds, and vinyl cyan compounds

ABS graft copolymer 20 to produced by a method comprising a system

80 parts by weight; And

b) 20 to styrene copolymer having a weight average molecular weight of 80,000 to 200,000

80 parts by weight

It provides a thermoplastic resin composition comprising a.

Hereinafter, the present invention will be described in detail.

The present inventors are studying a method for preparing an ABS graft copolymer having excellent thermal stability and impact resistance, and a reducing agent for improving the efficacy of an activator for promoting the initiation reaction of the peroxide in the step of initiating the polymerization reaction using the peroxide. As a result of preparing the ABS graft copolymer, the graft ratio and the molecular weight of the acrylonitrile-styrene copolymer were remarkably improved, and thus the impact resistance, the chemical resistance, and the thermal stability were remarkably improved. Was done.

The method for preparing the ABS graft copolymer of the present invention is characterized by including polymerizing a polybutadiene rubber polymer, an aromatic vinyl compound, and a vinyl cyan compound using a peroxide, an activator, and a reducing agent.

The peroxide used in the present invention is preferably included in 0.05 to 0.5 parts by weight based on 100 parts by weight of the monomer. If the content is less than 0.05 parts by weight, there is a problem that the reaction conversion rate is lowered, and if the content exceeds 0.5 parts by weight, there is a problem that the molecular weight of the resulting polymer is reduced.

The peroxide is used 30 ~ 40% by weight of the total amount used in the polymerization reaction start step, 30 to 40% by weight of the total amount used in the monomer emulsion administration step after the start of the polymerization, the total amount used in the aging step after completion of the monomer emulsion It is recommended to use 20 to 30% by weight.

As the peroxide, organic peroxides such as tertiary butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, or inorganic peroxides such as potassium persulfate salt may be used.

The activator used in the present invention serves to accelerate the initiation reaction of the peroxide.

The activator is preferably included in 0.0004 to 0.005 parts by weight based on 100 parts by weight of the monomer. If the content is less than 0.0004 parts by weight, there is a problem that the polymerization rate is slow, if it exceeds 0.005 parts by weight, there is a problem that the polymerization rate is too fast to lower the molecular weight of the resulting polymer.

The activating agent may be sodium formaldehyde succilate, sodium ethylenediamine tetraacetate, ferrous sulfate, dextrose, sodium pyrrolate, or sodium sulfite, preferably ferrous sulfate or sodium pyrrolate It is to use, and more preferably, 0.0001 to 0.002 parts by weight of ferrous sulfate and 0.001 to 0.02 parts by weight of sodium pyrolate are used in combination.

The reducing agent used in the present invention serves to improve the efficacy of the activator.

The reducing agent is preferably included in 0.001 to 0.05 parts by weight based on 100 parts by weight of the monomer. If the content is less than 0.001 parts by weight, there is little effect of increasing the molecular weight of the acrylonitrile-styrene copolymer, and if it exceeds 0.05 parts by weight, the graft ratio of the resulting graft copolymer is lowered.

The reducing agent may be a mixture of sodium sulfite, 2-hydroxy-2-sulfinatoacetic acid sodium salt, and 2-hydroxy-2-sulfonatoacetic acid sodium salt, in particular sodium sulfite 30-40 wt%, 2 It is preferable that it is a mixture of 50-60 weight% of sodium hydroxy-2-sulfinatoacetic acid sodium salt, and 10-20 weight% of 2-hydroxy-2-sulfonatoacetic acid sodium salt.

In the preparation of the ABS graft copolymer of the present invention, the polymerization initiation reaction occurs at 40 to 50 ° C., and then the reaction temperature is continuously raised to finally reach 70 to 80 ° C. to terminate the polymerization reaction. The polymerization is preferably carried out for 3 to 8 hours, wherein the polymerization conversion is preferably at least 95%.

ABS graft copolymer of the present invention can be prepared by the following method.

a) initiation of polymerization of peroxides

This step is carried out in the polymerization reactor, i) 40 to 70 parts by weight of polybutadiene rubber polymer, ii) up to 20 parts by weight of aromatic vinyl compound, i) up to 10 parts by weight of vinyl cyan compound, i) 0.015 to 0.2 parts by weight of peroxide, i) activation 0.0002 to 0.0025 parts by weight, and iii) 0.0005 to 0.025 part by weight of reducing agent to initiate a polymerization reaction.

The polybutadiene rubber polymer of iii) is preferably included in an amount of 40 to 70 parts by weight based on 100 parts by weight of the monomer. If the content is less than 40 parts by weight, there is a problem that the economic efficiency is lowered, and if the content is more than 70 parts by weight, the graft ratio of the resulting graft copolymer is lowered to obtain the required physical properties.

The average particle diameter of the polybutadiene rubber polymer is preferably 2500 to 3500 mm 3.

The aromatic vinyl compound of ii) is preferably included at most 20 parts by weight based on 100 parts by weight of the monomer.

As the aromatic vinyl compound, styrene, alpha methyl styrene, alpha ethyl styrene, paramethyl styrene, or the like may be used, and styrene is particularly preferable.

The vinylcyan compound of iii) is preferably included at most 10 parts by weight based on 100 parts by weight of the monomer.

As the vinyl cyan compound, acrylonitrile, methacrylonitrile, ethacrylonitrile, or the like may be used, and in particular, acrylonitrile is preferably used.

As the third monomer, maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-phenylmaleimide, methyl methacrylate, methyl acrylate, butyl acrylate, acrylic acid, Vinyl monomers, such as maleic anhydride, can be used further.

The peroxide of (i), the activator of (i), and the reducing agent of (i) may use the same components as described above.

The polymerization initiation reaction is carried out at 30 to 40 ° C, and as the polymerization proceeds, the temperature is continuously raised to finally reach 80 ° C.

b) monomer emulsion input

This step comprises: i) 20 to 40 parts by weight of an aromatic vinyl compound, ii) 10 to 20 parts by weight of a vinyl cyan compound, i) 0.5 to 1.5 parts by weight of an emulsifier, i) 0.015 to 0.2 parts by weight of peroxide, and ) Is a step of continuously adding a monomer emulsion containing 0.2 to 0.5 parts by weight of a molecular weight regulator.

Emulsifiers such as alkyl aryl sulfonates, alkali methyl alkyl sulfates, sulfonated alkyl esters, fatty acid soaps, alkali salts of rosin acids, and reactive emulsifiers may be used, and these may be used in combination. .

Mercaptans may be used as the molecular weight modifier of (i), and in particular, tertiary dodecyl mercaptan is preferably used.

c) ripening step

In this step, after the addition of the monomer emulsion is completed, the polymerization reactor is matured by iii) 0.01 to 0.15 parts by weight of peroxide, ii) 0.0002 to 0.0025 parts by weight of activator, and 0.0005 to 0.025 parts by weight of reducing agent.

The maturation is carried out at 70 to 80 ℃, and carried out for 1 to 2 hours to terminate the polymerization reaction.

The polymerization conversion rate of the ABS graft copolymer prepared according to the polymerization reaction of the present invention is preferably 95% or more.

The graft copolymer polymerized as described above is agglomerated with a flocculant such as sulfuric acid, MgSO ₄ , CaCl _2, or Al ₂ (SO ₄ ) ₃ , and then washed, dehydrated and dried to obtain a powder.

In another aspect, the present invention provides a thermoplastic resin composition prepared by mixing the ABS graft copolymer prepared by the above method and a styrene copolymer having a weight average molecular weight of 80,000 to 200,000.

It is preferably included 20 to 80 parts by weight of the ABS graft copolymer prepared by the above method with respect to 100 parts by weight of the thermoplastic resin composition, 20 to 80 parts by weight of the styrene-based copolymer having a weight average molecular weight of 80,000 to 200,000. It is preferable.

The styrenic copolymer may be polystyrene, styrene-alphamethylstyrene copolymer, acrylonitrile-styrene copolymer, terpolymer of acrylonitrile-styrene-alphamethylstyrene, styrene-methylmethacrylate copolymer, styrene-alpha Methylstyrene-methylmethacrylate terpolymer, or a mixture thereof can be used. In particular, it is preferable to use an acrylonitrile-styrene copolymer.

In addition, the present invention, if necessary, oxidizing stabilizers such as phenol, phosphorus, sulfur, light stabilizers such as benzotriazole and amine, lubricants such as stearyl alcohol and ethylenebisstearylamide, ultraviolet absorbers, plasticizers and coloring agents. , Additives such as flame retardants, enhancers, compatibilizers, blowing agents, wood flours, fillers, metal powders, antibacterial agents, antifungal agents, silicone oils, or coupling agents may be further used.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

EXAMPLE

Examples 1 and 2, and Comparative Example 1. Preparation of ABS graft copolymer

Example 1

(Polymerization start stage)

In a polymerization reactor equipped with a heating device, 60 parts by weight of a polybutadiene rubber polymer having an average particle diameter of about 3000 kPa, 145 parts by weight of ion-exchanged water, 0.1 part by weight of potassium rosinate as an emulsifier, and 0.1 part by weight of cumene hydroperoxide as a peroxide were added. . When the temperature inside the reactor reached 50 ° C., 0.0002 parts by weight of a mixture of sodium pyrrolate and ferrous sulfate as an activator, sodium sorbite as a reducing agent, sodium salt of 2-hydroxy-2-sulfinatoacetic acid, and 2-hydride The polymerization reaction was initiated by adding 0.002 parts by weight of a mixture of oxy-2-sulfonatoacetic acid sodium salt.

(Monomer emulsion input step)

In a separate mixing device, 11 parts by weight of acrylonitrile as a vinyl cyan compound, 29 parts by weight of styrene as an aromatic vinyl compound, 40 parts by weight of ion-exchanged water, 0.1 part by weight of cumene hydroperoxide as peroxide, and 1.0 weight of potassium rosin as emulsifier The parts were mixed to prepare a monomer emulsion. The monomer emulsion was continuously added to the reactor for about 3 hours immediately after the start of the polymerization reaction. The reaction temperature was gradually raised to 70 ° C.

(Mature stage)

After the addition of the monomer emulsion, 0.0002 parts by weight of a mixture of sodium pyrrolate and ferrous sulfate as an activator, sodium sulphite as a reducing agent, 2-hydroxy-2-sulfinatoacetic acid sodium salt, and 2-hydroxy 0.002 parts by weight of a mixture of 2-shalponatoacetic acid sodium salt was added to the reactor, the reaction temperature was raised to 80 ° C. for 1 hour, and the reaction was terminated to obtain an ABS graft copolymer. The polymerization conversion rate at this time was 98%.

Example 2

0.004 parts by weight of a mixture of sodium sulphite, 2-hydroxy-2-sulfinatoacetic acid sodium salt, and 2-hydroxy-2-sulfonatoacetic acid sodium salt as a reducing agent in the polymerization start step and the aging step in Example 1 Except that each was carried out in the same manner as in Example 1 to obtain an ABS graft copolymer.

Comparative Example 1

Except not using a reducing agent in Example 1 was carried out in the same manner as in Example 1 to obtain an ABS graft copolymer.

Experimental Example 1

The antioxidant was added to the ABS graft copolymers prepared in Examples 1 or 2 and Comparative Example 1, then agglomerated with 15% magnesium sulfate aqueous solution, washed, and dried to obtain a powdery ABS graft copolymer. . The molecular weight, molecular weight distribution, graft ratio, and thermal stability of the ABS graft copolymer were measured by the following method, and the results are shown in Table 1 below.

A) weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)-agglomerated and dried the sol portion separated in the graft rate measurement to obtain a styrene copolymer, dissolved in THF gel permeation chromatography (GPC) analysis The molecular weight and molecular weight distribution were measured using the apparatus.

B) Graft rate-After stirring 2 g of powdered graft copolymer with 100 mL of acetone for 24 hours to dissolve the grafted styrene copolymer in the rubber polymer, the gel and the sol were separated by ultracentrifugation, The graft ratio was calculated by one.

[Equation 1]

C) Thermal Stability-The time for which the graft copolymer in powder state was oxidized at 190 ° C. At this time, TG / DTA 320 (Seiko Instrument) was used as the thermal analyzer.

division Example 1 Example 2 Comparative Example 1 Weight average molecular weight (Mw) 94,000 97,000 72,000 Molecular Weight Distribution (Mw / Mn) 2.44 2.59 2.38 Graft Rate (%) 32 31 34 Thermal stability (oxidation time: minutes) 67 68 45

Through Table 1, Examples 1 and 2 subjected to the polymerization reaction using a peroxide, an activator, and a reducing agent according to the present invention is ABS graft compared to Comparative Example 1, which carried out the polymerization reaction without using a reducing agent The molecular weight of the copolymer was increased by about 20%, it was confirmed that the thermal stability of the powder-based ABS graft copolymer is significantly improved.

Examples 3 to 4 and Comparative Example 2. Preparation of rubber-reinforced thermoplastic resin composition

Example 3

75 parts by weight of the styrene copolymer (styrene-based acrylonitrile-styrene copolymer, weight average molecular weight 110,000, acrylonitrile content 28% by weight) and a small amount of 25 parts by weight of the ABS graft copolymer prepared in Example 1 The heat stabilizer and the lubricant were combined and then mixed in an extruder to obtain a rubber-reinforced thermoplastic resin composition.

Example 4

Except for using the ABS graft copolymer prepared in Example 3 in Example 3 was carried out in the same manner as in Example 3 to obtain a rubber-reinforced thermoplastic resin composition.

Comparative Example 2

Except for using the ABS graft copolymer prepared in Comparative Example 1 in Example 3 was carried out in the same manner as in Example 3 to obtain a rubber-reinforced thermoplastic resin composition.

Experimental Example 2

The mechanical properties of the rubber-reinforced thermoplastic resin compositions prepared in Examples 3 or 4 and Comparative Example 2 were measured by the following method, and the results are shown in Table 2 below.

A) Izod impact strength-measured according to ASTM D256. The thickness of the specimen is 1/4 inch.

B) Melt flow rate-measured according to ASTM D1238 under the condition of 220 ° C. and 10 kg.

C) Tensile Test-Measured according to ASTM D638.

D) surface gloss-measured according to ASTM D528 at an angle of 45 °.

division Example 3 Example 4 Comparative Example 2 Furtherance ABS graft copolymer 25 parts by weight of ABS graft copolymer of Example 1 25 parts by weight of the ABS graft copolymer of Example 2 25 parts by weight of the ABS graft copolymer of Comparative Example 1 Styrene copolymer 75 75 75 Mechanical properties Impact strength 30 32 23 Flow index 22 23 23 The tensile strength 450 449 450 Surface gloss 96 96 95

Through Table 2, in the case of Example 3 and Example 4 using the ABS graft copolymer of Examples 1 and 2 prepared according to the present invention it can be seen that the impact strength significantly increased compared to Comparative Example 2 there was.

According to the method of the present invention, acrylonitrile-butadiene-styrene graft not only can significantly improve the graft rate, the molecular weight and productivity of the acrylonitrile-styrene copolymer, but also has excellent impact resistance, chemical resistance, and thermal stability. Copolymers can be prepared. In addition, the ABS graft copolymer prepared according to the present invention may not only improve the thermal stability of the powdered ABS graft copolymer, but also significantly improve the impact strength of the rubber-reinforced thermoplastic resin including the same. It has an effect.

Claims (12)

A method for producing an ABS graft copolymer, comprising: polymerizing a polybutadiene rubber polymer, an aromatic vinyl compound, and a vinyl cyan compound using a peroxide, an activator, and a reducing agent. The method of claim 1, Method for producing an ABS graft copolymer comprising the peroxide in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the monomer. The method of claim 1, The method for producing an ABS graft copolymer, wherein the peroxide is selected from the group consisting of tertiary butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzenehydro peroxide, and potassium persulfate salt. The method of claim 1, Method for producing an ABS graft copolymer comprising the activator is 0.0004 to 0.005 parts by weight based on 100 parts by weight of the monomer. The method of claim 1, A method for producing an ABS graft copolymer, wherein the activator is at least one selected from the group consisting of sodium formaldehyde sloxylate, sodium ethylenediamine tetraacetate, ferrous sulfate, dextrose, sodium pyrrolate, and sodium sulfite. The method of claim 1, Method for producing an ABS graft copolymer comprising the reducing agent in an amount of 0.001 to 0.05 parts by weight based on 100 parts by weight of the monomer. The method of claim 1, Preparation of ABS graft copolymers wherein the reducing agent is at least one selected from the group consisting of sodium sulphite, 2-hydroxy-2-sulfinatoacetic acid sodium salt, and 2-hydroxy-2-sulfonatoacetic acid sodium salt Way. The method of claim 1, a) i) 40 to 70 parts by weight of a polybutadiene rubber polymer; Ii) up to 20 parts by weight of an aromatic vinyl compound; Iii) up to 10 parts by weight of a vinylcyan compound; Iii) 0.015 to 0.2 parts by weight of peroxide; Iii) 0.0002 to 0.0025 parts by weight of activator; And Iii) 0.0005 to 0.025 parts by weight of reducing agent Initiating the polymerization reaction; b) reactants of step a) Iii) 20 to 40 parts by weight of an aromatic vinyl compound; Ii) 10 to 20 parts by weight of the vinyl cyan compound; V) 0.5 to 1.5 parts by weight of emulsifier; Iii) 0.015 to 0.2 parts by weight of peroxide; And Iii) 0.2 to 0.5 parts by weight of molecular weight regulator Injecting a monomer emulsion comprising a; And c) After the addition of the monomer emulsion in step b) is completed Iii) 0.01 to 0.15 parts by weight of peroxide; Ii) 0.0002 to 0.0025 parts by weight of activator; And Iii) 0.0005 to 0.025 parts by weight of reducing agent Aging step Method for producing an ABS graft copolymer comprising a. An ABS graft copolymer composition prepared by a method comprising polymerizing a polybutadiene rubber polymer, an aromatic vinyl compound, and a vinyl cyan compound using a peroxide, an activator, and a reducing agent. The method of claim 9, The ABS graft copolymer composition a) 40 to 70 parts by weight of a polybutadiene rubber polymer; b) 15 to 30 parts by weight of an aromatic vinyl compound; c) 10 to 25 parts by weight of the vinyl cyan compound; d) 0.6 to 2.0 parts by weight of emulsifier; e) 0.1 to 1.0 parts by weight of molecular weight modifier; f) 0.05 to 0.5 parts by weight of peroxide; g) 0.0004 to 0.005 parts by weight of activator; And h) 0.001 to 0.05 parts by weight of reducing agent ABS graft copolymer composition comprising a. In the thermoplastic resin composition, a) in polybutadiene rubber using peroxides, activators and reducing agents To polymerize coalescing, aromatic vinyl compounds, and vinyl cyan compounds ABS graft copolymer 20 to produced by a method comprising a system 80 parts by weight; And b) 20 to styrene copolymer having a weight average molecular weight of 80,000 to 200,000 80 parts by weight Thermoplastic resin composition comprising a. The method of claim 11, The styrene copolymer is polystyrene, styrene-alphamethylstyrene copolymer, acrylonitrile-styrene copolymer, terpolymer of acrylonitrile-styrene-alphamethylstyrene, styrene-methylmethacrylate copolymer, styrene-alpha A thermoplastic resin composition selected from the group consisting of methyl styrene-methyl methacrylate terpolymer, and mixtures thereof.